Understanding Hallucinations (Part I) (UH-1)

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Psychotic symptoms (hallucinations and delusions) are present in several psychiatric and neurological disorders as well as in the general population. Effective treatment strategies for these symptoms in all patients are lacking and treatment-response can presently not be predicted. To date, the exact pathophysiological mechanism of these symptoms remains unknown. By investigating (subtypes) of hallucinations and delusions in all populations, a common pathway may be found, leading to more effective treatment options. Alternatively, different subtypes may be associated with different pathophysiological mechanisms.

The number of clusters of patients with shared symptom profiles as determined by latent class analysis, and the difference in scores on cognitive assessment between these identified clusters. [ Time Frame: Three years ]

Secondary Outcome Measures :

The internal consistency, test-retest reliability, inter-rater reliability, criterion validity and construct validity of a newly developed questionnaire. [ Time Frame: Two years ]

The difference in scores on cognitive assessment between participant groups with and without psychotic symptoms. [ Time Frame: Three years ]

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Ages Eligible for Study:

18 Years and older (Adult, Older Adult)

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

Sampling Method:

Non-Probability Sample

Study Population

We aim to include subjects of each of the following diagnostic groups, both with and without psychotic symptoms:

patients with schizophrenia spectrum disorders

patients with borderline personality disorder (BPD)

patients with hearing impairment

patients with visual loss

patients with Parkinson's disease (PD)

patients with Alzheimer's disease (AD)

patients with Lewy Body dementia (DLB)

patients with post-traumatic stress disorder (PTSD)

patients with delirium

healthy individuals

patients with mood disorder

Criteria

Inclusion Criteria:

age > 18 years

mentally competent

in case of delirium: family member able to give informed consent

Individuals with hallucinations will have to experience at least one episode of hallucinations over the last month.

Individuals without hallucinations: no current hallucinations and a history of maximum 1 episode of hallucinations with a maximum duration of 1 week, at least two years ago.

Exclusion Criteria:

Age <18)

Participants that cannot read, speak or understand Dutch

For all included diagnostic groups except delirium: Mentally incompetent individuals who are not capable to provide informed consent, as determined by their treating physician.